Short-term low-intensity blood flow restricted interval training improves both aerobic fitness and muscle strength.

The present study aimed to analyze and compare the effects of four different interval-training protocols on aerobic fitness and muscle strength. Thirty-seven subjects (23.8 ± 4 years; 171.7 ± 9.5 cm; 70 ± 11 kg) were assigned to one of four groups: low-intensity interval training with (BFR, n = 10) or without (LOW, n = 7) blood flow restriction, high-intensity interval training (HIT, n = 10), and combined HIT and BFR (BFR + HIT, n = 10, every session performed 50% as BFR and 50% as HIT). Before and after 4 weeks training (3 days a week), the maximal oxygen uptake (VO2max ), maximal power output (Pmax ), onset blood lactate accumulation (OBLA), and muscle strength were measured for all subjects. All training groups were able to improve OBLA (BFR, 16%; HIT, 25%; HIT + BFR, 22%; LOW, 6%), with no difference between groups. However, VO2max and Pmax improved only for BFR (6%, 12%), HIT (9%, 15%) and HIT + BFR (6%, 11%), with no difference between groups. Muscle strength gains were only observed after BFR training (11%). This study demonstrates the advantage of short-term low-intensity interval BFR training as the single mode of training able to simultaneously improve aerobic fitness and muscular strength.

Stroking parameters during continuous and intermittent exercise in regional-level competitive swimmers.

This study aimed to determine whether maximal lactate steady state (MLSS) represents a boundary above which not only physiological but also technical changes occur. On different days, 13 male swimmers (23 ± 9 years) performed the following tests: 1) a 400-m all-out swim, to determine maximal aerobic speed (S-400); 2) a series of 30-min sub-maximal swims, to determine continuous MLSS (MLSSc), and; 3) a series of 12×150 s sub-maximal swims, to determine intermittent MLSS (MLSSi). Stroke rate (SR), distance per stroke cycle (DS) and stroke index (SI) were analyzed at and above (102.5%) MLSSc and MLSSi. MLSSi (1.17 ± 0.09 m.s (- 1)) was significantly higher than MLSSc (1.13 ± 0.08 m.s (- 1)) while blood lactate concentration (mmol.L (- 1)) was similar between the 2 conditions (4.3 ± 1.1 and 4.4 ± 1.5, respectively). The increase in SR and decreases in DS and SI were significant during MLSSi, 102.5% MLSSc and 102.5% MLSSi. During MLSSc, DS also decreased significantly (- 3.6%) but with no change in SR or SI. Thus, stroking technique of regional-level competitive swimmers changes over time when they swim at or above MLSS. This is the case during both continuous and intermittent swimming, despite steady state blood lactate concentrations.